dr. hooman yaghoobzadeh joins us right now. what does this study tell us, doctor? >> well, we've never had a study that compares head to head the two ways that we typically work up patients who have chest pain. this study takes a look to see when somebody comes in with chest pain what, tests the doctor should order. one test is a cat scan which is a way to actually look at arteries and see if there are blockages and how tight the block are. the other test is a stress test which doesn't look at the actual blockage but looks at blood flow to the heart muscle. each test has its benefits and limitations and the results of this study show that both tests are very good at keeping the rates of heart attack and death at two years very are low. >> axelrod: how will this best be applied? >> if a doctor doesn't know if somebody has heart disease or not and they're not on cholesterol medicines or rasp rin, a cat scan may be a better idea if the doctor wants to fiend out more about what happens to heart rate and blood pressure with exercise a stress test would be a better idea.